Personal electronic devices are becoming increasingly ubiquitous and integrated into daily user routines. For example, an information worker may begin working on a word processing document on a desktop computer, transfer the document file to a notebook computer to become mobile, and then to a tablet computer or smart phone for travel. A business executive may take a picture on a smart phone, and transfer the image file to a digital frame in her office. A film producer may begin watching a movie on a tablet computer in a car, and transfer the movie file to a workstation at home for editing.
The ability to transfer files between different devices is a major convenience in a time when users have multiple personal electronic devices. Data unit transfer techniques allow a user to create, modify and consume content at the convenience of the user, which in turn enhances user productivity and user experience. However, conventional data unit transfer techniques need some level of manual intervention by a user. For example, a user may need to copy a file from one device to a data storage device, such as a universal serial bus (USB) flash drive or network server, and then copy the file from the data storage device to another device. In another example, a user may transfer a file as an attachment to a message, such as an email message, a short messaging service (SMS) message, or a multimedia messaging service (MMS) message. These file transfer techniques are limiting, cumbersome and time consuming. Some file transfer techniques attempt to limit manual intervention, such as “bump” technology which activates a file transfer when two devices touch, or a gesture interface that activates a file transfer in response to a hand gesture. However, these file transfer techniques still need a significant amount of manual intervention by a user, particularly if the user has a disability. Therefore, one design goal for personal electronic devices is to reduce manual intervention to activate file transfers.